The present invention is applicable to the formation of a perimeter-type building foundation comprising a footing and wall atop said footing, both constructed from a hardenable plastic material, and is especially applicable to the formation of such foundations using wood forms and a concrete mixture. The present invention is also useful in forming such foundations using any hardenable plastic material having strength characteristics suitable for a building foundation.
The art of forming perimeter-type building foundations using a plastic concrete mixture is well known and is generally accomplished in a multi-step process. A first form comprising elongate vertical walls is constructed using elongate members such as sheets of plywood to define a space therebetween that has the general shape of an elongate footing of predetermined length. The first form is inserted and supported in a trench prepared in the earth and thereafter a predetermined amount of plastic concrete material is prepared and poured into the first form so as to form a footing therein.
Once the footing has hardened, a second form also comprising vertical walls is constructed on the top surface of the footing to define an elongate space between the vertical walls thereof that has the general shape of an elongate wall of predetermined length and height. A second predetermined amount of plastic concrete material is prepared and poured into the second form so as to form a wall therein. The process is completed by removing the first and second forms from the hardened perimeter-type foundation.
Current building codes generally mandate that the wall formed by this process include a longitudinal portion projecting from the bottom thereof and intruding into the footing so as to anchor the wall therein. Such codes generally require that this integral projection or "key" have both a width dimension and a depth dimension of at least 1.5 inches in order to insure that a standard 6-inch wall is adequately anchored in its footing.
In the current state of the art, the initial step in forming the key is to move an elongate member such as a piece of 2.times.4 lumber into the top surface of an elongate footing during the plastic state thereof so as to form a central, longitudinal keyway having the prerequisite 1.5 inch.times.1.5 inch configuration. Once the footing is hardened, the second form is mounted atop the footing with its interior exposed to the keyway and thereafter a second predetermined amount of the plastic concrete material is poured into the space defined by the second form with a portion thereof flowing into the elongate keyway which will thereafter harden to form a key to solidly anchor the wall in its footing.
A major drawback in the formation of concrete perimeter-type building foundations is the lack of an efficient form apparatus and method for securing the second form atop the hardened footing until the wall has been poured and allowed to harden. Although several form mounting methods are being used, the more prevalent procedure is to anchor the second form upon the hardened footing using form-ties and top-ties.
Form-ties are elongate metal members extending transversely across the top of the footing and having a pair of upturned flanges extending from each end. A predetermined spacing is provided between each pair of upturned flanges so as to permit the reception of the lower edges of a pair of spaced, opposed plywood sheets or the like comprising the sidewalls of the second form.
Top-ties are transversely extending elongate metal members having a pair of downturned flanges extending from each end. Each downturned flange is adapted to be fastened to the top outer edge of one of the sidewalls of the second form, and is spaced from the opposing downturned flange by a predetermined distance so as to separate the form sidewalls according to a predetermined wall-width.
In use, a sufficient quantity of form-ties are placed transversely atop the solid footing so that their respective upturned flanges form longitudinal parallel lines relative to the elongate footing. The sidewalls of the second form are inserted into and receive lateral anchoring support from the spaced upturned flanges of the form-ties. Erection of the second form is completed by attaching a plurality of top-ties transversely to the top edges of each of the sidewalls.
Several difficulties attend this method for anchoring the second form atop the solid footing. First, a large number of form-ties are required to anchor a standard peripheral-type building foundation, requiring a sizable initial investment to obtain a sufficient quantity of form-ties. More importantly, the hardened wall captures the mid-portion of each form-tie and, hence, unlike the top-ties which are thereafter removed for additional applications, the form-ties are integral to the foundation and cannot be removed. Accordingly, the investment in form-ties is a continuing one.
Moreover, the foregoing process involves an inordinate amount of labor in accurately positioning the form-ties so as to insure the trueness and desired positioning of the walls. Since the form-ties are not fastened to the top surface of the footing until captured by the poured wall, the application of any lateral force thereto causes the form-ties to move and necessitates extensive realignment of the form-ties during the insertion of the sidewalls.
What is needed therefore, and what the present invention provides, is a method for obtaining lateral anchoring support for a wall form atop a solid concrete footing which eliminates inordinate investments in form-ties, simplifies the insertion process thereby lowering labor costs, and insures that the elongate key will be centered along the longitudinal centerline of the elongate wall.